Polymers functionalized with nitroso compounds

ABSTRACT

A method for preparing a functionalized polymer, the method comprising the steps of: (i) polymerizing monomer with a coordination catalyst to form a reactive polymer; and (ii) reacting the reactive polymer with a nitroso compound.

This application claims the benefit of U.S. Non-Provisional applicationSer. No. 12/347,493, filed Dec. 31, 2008, which is incorporated hereinby reference.

FIELD OF THE INVENTION

One or more embodiments of the present invention relate tofunctionalized polymers and methods for their manufacture.

BACKGROUND OF THE INVENTION

In the art of manufacturing tires, it is desirable to employ rubbervulcanizates that demonstrate reduced hysteresis, i.e., less loss ofmechanical energy to heat. For example, rubber vulcanizates that showreduced hysteresis are advantageously employed in tire components, suchas sidewalls and treads, to yield tires having desirably low rollingresistance. The hysteresis of a rubber vulcanizate is often attributedto the free polymer chain ends within the crosslinked rubber network, aswell as the dissociation of filler agglomerates.

Functionalized polymers have been employed to reduce the hysteresis ofrubber vulcanizates. The functional group of the functionalized polymermay reduce the number of free polymer chain ends via interaction withfiller particles. Also, the functional group may reduce filleragglomeration. Nevertheless, whether a particular functional groupimparted to a polymer can reduce hysteresis is often unpredictable.

Functionalized polymers may be prepared by post-polymerization treatmentof reactive polymers with certain functionalizing agents. However,whether a reactive polymer can be functionalized by treatment with aparticular functionalizing agent can be unpredictable. For example,functionalizing agents that work for one type of polymer do notnecessarily work for another type of polymer, and vice versa.

Lanthanide-based catalyst systems are known to be useful forpolymerizing conjugated diene monomers to form polydienes having a highcontent of cis-1,4 linkage. The resulting cis-1,4-polydienes may displaypseudo-living characteristics in that, upon completion of thepolymerization, some of the polymer chains possess reactive ends thatcan react with certain functionalizing agents to yield functionalizedcis-1,4-polydienes.

The cis-1,4-polydienes produced with lanthanide-based catalyst systemstypically have a linear backbone, which is believed to provide bettertensile properties, higher abrasion resistance, lower hysteresis, andbetter fatigue resistance as compared to the cis-1,4-polydienes preparedwith other catalyst systems such as titanium-, cobalt-, and nickel-basedcatalyst systems. Therefore, the cis-1,4-polydienes made withlanthanide-based catalysts are particularly suitable for use in tirecomponents such as sidewalls and treads. However, one disadvantage ofthe cis-1,4-polydienes prepared with lanthanide-based catalysts is thatthe polymers exhibit high cold flow due to their linear backbonestructure. The high cold flow causes problems during storage andtransport of the polymers and also hinders the use of automatic feedingequipment in rubber compound mixing facilities.

Because functionalized polymers are advantageous, especially in themanufacture of tires, there exists a need to develop new functionalizedpolymers that give reduced hysteresis and reduced cold flow.

SUMMARY OF THE INVENTION

One or more embodiments of the present invention provide a method forpreparing a functionalized polymer, the method comprising the steps of:(i) polymerizing monomer with a coordination catalyst to form a reactivepolymer; and (ii) reacting the reactive polymer with a nitroso compound.

One or more embodiments of the present invention provide afunctionalized cis-1,4-polydiene defined by the formula:

where π is a cis-1,4-polydiene chain having a cis-1,4-linkage contentthat is greater than 60%, where β is a mono-valent organic group, andwhere R′ is a hydrogen atom or a mono-valent organic group.

One or more embodiments of the present invention provide afunctionalized cis-1,4-polydiene prepared by the steps of (i)polymerizing conjugated diene monomer with a coordination catalyst toform a reactive cis-1,4-polydiene having a cis-1,4-linkage content thatis greater than 60%; and (ii) reacting the reactive cis-1,4-polydienewith a nitroso compound.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graphical plot of cold-flow gauge (mm at 8 min) versusMooney viscosity (ML 1+4 at 100° C.) for functionalizedcis-1,4-polybutadiene prepared according to one or more embodiments ofthe present invention as compared to unfunctionalizedcis-1,4-polybutadiene.

FIG. 2 is a graphical plot of hysteresis loss (tan δ) versus Mooneyviscosity (ML 1+4 at 130° C.) for vulcanizates prepared fromfunctionalized cis-1,4-polybutadiene prepared according to one or moreembodiments of the present invention as compared to vulcanizatesprepared from unfunctionalized cis-1,4-polybutadiene.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

According to one or more embodiments of the present invention, areactive polymer is prepared by polymerizing conjugated diene monomerwith a coordination catalyst, and this reactive polymer can then befunctionalized by reaction with a nitroso compound. The resultantfunctionalized polymers can be used in the manufacture of tirecomponents. In one or more embodiments, the resultant functionalizedpolymers, which include cis-1,4-polydienes, exhibit advantageouscold-flow resistance and provide tire components that exhibitadvantageously low hysteresis.

Examples of conjugated diene monomer include 1,3-butadiene, isoprene,1,3-pentadiene, 1,3-hexadiene, 2,3-dimethyl-1,3-butadiene,2-ethyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 3-methyl-1,3-pentadiene,4-methyl-1,3-pentadiene, and 2,4-hexadiene. Mixtures of two or moreconjugated dienes may also be utilized in copolymerization.

In one or more embodiments, the reactive polymer is prepared bycoordination polymerization, wherein monomer is polymerized by using acoordination catalyst system. The key mechanistic features ofcoordination polymerization have been discussed in books (e.g., Kuran,W., Principles of Coordination Polymerization; John Wiley & Sons: NewYork, 2001) and review articles (e.g., Mulhaupt, R., MacromolecularChemistry and Physics 2003, volume 204, pages 289-327). Coordinationcatalysts are believed to initiate the polymerization of monomer by amechanism that involves the coordination or complexation of monomer toan active metal center prior to the insertion of monomer into a growingpolymer chain. An advantageous feature of coordination catalysts istheir ability to provide stereochemical control of polymerizations andthereby produce stereoregular polymers. As is known in the art, thereare numerous methods for creating coordination catalysts, but allmethods eventually generate an active intermediate that is capable ofcoordinating with monomer and inserting monomer into a covalent bondbetween an active metal center and a growing polymer chain. Thecoordination polymerization of conjugated dienes is believed to proceedvia π-allyl complexes as intermediates. Coordination catalysts can beone-, two-, three- or multi-component systems. In one or moreembodiments, a coordination catalyst may be formed by combining a heavymetal compound (e.g., a transition metal compound or a lanthanidecompound), an alkylating agent (e.g., an organoaluminum compound), andoptionally other co-catalyst components (e.g., a Lewis acid or a Lewisbase). In one or more embodiments, the heavy metal compound may bereferred to as a coordinating metal compound.

Various procedures can be used to prepare coordination catalysts. In oneor more embodiments, a coordination catalyst may be formed in situ byseparately adding the catalyst components to the monomer to bepolymerized in either a stepwise or simultaneous manner. In otherembodiments, a coordination catalyst may be preformed. That is, thecatalyst components are pre-mixed outside the polymerization systemeither in the absence of any monomer or in the presence of a smallamount of monomer. The resulting preformed catalyst composition may beaged, if desired, and then added to the monomer that is to bepolymerized.

Useful coordination catalyst systems include lanthanide-based catalystsystems. These catalyst systems may advantageously producecis-1,4-polydienes that, prior to quenching, have reactive chain endsand may be referred to as pseudo-living polymers. While othercoordination catalyst systems may also be employed, lanthanide-basedcatalysts have been found to be particularly advantageous, andtherefore, without limiting the scope of the present invention, will bediscussed in greater detail.

The practice of one or more embodiments of the present invention is notlimited by the selection of any particular lanthanide-based catalyst. Inone or more embodiments, the catalyst composition may include alanthanide compound, an alkylating agent, and a halogen-containingcompound that includes one or more labile halogen atoms. Where thelanthanide compound and/or alkylating agent include one or more labilehalogen atoms, the catalyst need not include a separatehalogen-containing compound; e.g., the catalyst may simply include ahalogenated lanthanide compound and an alkylating agent. In certainembodiments, the alkylating agent may include both an aluminoxane and atleast one other organoaluminum compound. In yet other embodiments, acompound containing a non-coordinating anion, or a non-coordinatinganion precursor, i.e., a compound that can undergo a chemical reactionto form a non-coordinating anion, may be employed in lieu of ahalogen-containing compound. In one embodiment, where the alkylatingagent includes an organoaluminum hydride compound, thehalogen-containing compound may be a tin halide as disclosed in U.S.Pat. No. 7,008,899, which is incorporated herein by reference. In theseor other embodiments, other organometallic compounds, Lewis bases,and/or catalyst modifiers may be employed in addition to the ingredientsor components set forth above. For example, in one embodiment, anickel-containing compound may be employed as a molecular weightregulator as disclosed in U.S. Pat. No. 6,699,813, which is incorporatedherein by reference.

Various lanthanide compounds or mixtures thereof can be employed. In oneor more embodiments, these compounds may be soluble in hydrocarbonsolvents such as aromatic hydrocarbons, aliphatic hydrocarbons, orcycloaliphatic hydrocarbons. In other embodiments, hydrocarbon-insolublelanthanide compounds, which can be suspended in the polymerizationmedium to form the catalytically active species, are also useful.

Lanthanide compounds may include at least one atom of lanthanum,neodymium, cerium, praseodymium, promethium, samarium, europium,gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium,lutetium, and didymium. Didymium may include a commercial mixture ofrare-earth elements obtained from monazite sand.

The lanthanide atom in the lanthanide compounds can be in variousoxidation states including but not limited to the 0, +2, +3, and +4oxidation states. Lanthanide compounds include, but are not limited to,lanthanide carboxylates, lanthanide organophosphates, lanthanideorganophosphonates, lanthanide organophosphinates, lanthanidecarbamates, lanthanide dithiocarbamates, lanthanide xanthates,lanthanide β-diketonates, lanthanide alkoxides or aryloxides, lanthanidehalides, lanthanide pseudo-halides, lanthanide oxyhalides, andorganolanthanide compounds.

Without wishing to limit the practice of the present invention, furtherdiscussion will focus on neodymium compounds, although those skilled inthe art will be able to select similar compounds that are based uponother lanthanide metals.

Neodymium carboxylates include neodymium formate, neodymium acetate,neodymium acrylate, neodymium methacrylate, neodymium valerate,neodymium gluconate, neodymium citrate, neodymium fumarate, neodymiumlactate, neodymium maleate, neodymium oxalate, neodymium2-ethylhexanoate, neodymium neodecanoate (a.k.a. neodymium versatate),neodymium naphthenate, neodymium stearate, neodymium oleate, neodymiumbenzoate, and neodymium picolinate.

Neodymium organophosphates include neodymium dibutyl phosphate,neodymium dipentyl phosphate, neodymium dihexyl phosphate, neodymiumdiheptyl phosphate, neodymium dioctyl phosphate, neodymiumbis(1-methylheptyl) phosphate, neodymium bis(2-ethylhexyl) phosphate,neodymium didecyl phosphate, neodymium didodecyl phosphate, neodymiumdioctadecyl phosphate, neodymium dioleyl phosphate, neodymium diphenylphosphate, neodymium bis(p-nonylphenyl) phosphate, neodymium butyl(2-ethylhexyl) phosphate, neodymium (1-methylheptyl) (2-ethylhexyl)phosphate, and neodymium (2-ethylhexyl) (p-nonylphenyl) phosphate.

Neodymium organophosphonates include neodymium butyl phosphonate,neodymium pentyl phosphonate, neodymium hexyl phosphonate, neodymiumheptyl phosphonate, neodymium octyl phosphonate, neodymium(1-methylheptyl) phosphonate, neodymium (2-ethylhexyl) phosphonate,neodymium decyl phosphonate, neodymium dodecyl phosphonate, neodymiumoctadecyl phosphonate, neodymium oleyl phosphonate, neodymium phenylphosphonate, neodymium (p-nonylphenyl) phosphonate, neodymium butylbutylphosphonate, neodymium pentyl pentylphosphonate, neodymium hexylhexylphosphonate, neodymium heptyl heptylphosphonate, neodymium octyloctylphosphonate, neodymium (1-methylheptyl)(1-methylheptyl)phosphonate, neodymium (2-ethylhexyl)(2-ethylhexyl)phosphonate, neodymium decyl decylphosphonate, neodymiumdodecyl dodecylphosphonate, neodymium octadecyl octadecylphosphonate,neodymium oleyl oleylphosphonate, neodymium phenyl phenylphosphonate,neodymium (p-nonylphenyl) (p-nonylphenyl) phosphonate, neodymium butyl(2-ethylhexyl)phosphonate, neodymium (2-ethylhexyl) butylphosphonate,neodymium (1-methylheptyl) (2-ethylhexyl)phosphonate, neodymium(2-ethylhexyl) (1-methylheptyl)phosphonate, neodymium (2-ethylhexyl)(p-nonylphenyl)phosphonate, and neodymium (p-nonylphenyl)(2-ethylhexyl)phosphonate.

Neodymium organophosphinates include neodymium butylphosphinate,neodymium pentylphosphinate, neodymium hexylphosphinate, neodymiumheptylphosphinate, neodymium octylphosphinate, neodymium(1-methylheptyl)phosphinate, neodymium (2-ethylhexyl)phosphinate,neodymium decylphosphinate, neodymium dodecylphosphinate, neodymiumoctadecylphosphinate, neodymium oleylphosphinate, neodymiumphenylphosphinate, neodymium (p-nonylphenyl) phosphinate, neodymiumdibutylphosphinate, neodymium dipentylphosphinate, neodymiumdihexylphosphinate, neodymium diheptylphosphinate, neodymiumdioctylphosphinate, neodymium bis(1-methylheptyl)phosphinate, neodymiumbis(2-ethylhexyl) phosphinate, neodymium didecylphosphinate, neodymiumdidodecylphosphinate, neodymium dioctadecylphosphinate, neodymiumdioleylphosphinate, neodymium diphenylphosphinate, neodymiumbis(p-nonylphenyl) phosphinate, neodymium butyl (2-ethylhexyl)phosphinate, neodymium (1-methylheptyl) (2-ethylhexyl)phosphinate, andneodymium (2-ethylhexyl)(p-nonylphenyl)phosphinate.

Neodymium carbamates include neodymium dimethylcarbamate, neodymiumdiethylcarbamate, neodymium diisopropylcarbamate, neodymiumdibutylcarbamate, and neodymium dibenzylcarbamate.

Neodymium dithiocarbamates include neodymium dimethyldithiocarbamate,neodymium diethyldithiocarbamate, neodymium diisopropyldithiocarbamate,neodymium dibutyldithiocarbamate, and neodymium dibenzyldithiocarbamate.

Neodymium xanthates include neodymium methylxanthate, neodymiumethylxanthate, neodymium isopropylxanthate, neodymium butylxanthate, andneodymium benzylxanthate.

Neodymium β-diketonates include neodymium acetylacetonate, neodymiumtrifluoroacetylacetonate, neodymium hexafluoroacetylacetonate, neodymiumbenzoylacetonate, and neodymium 2,2,6,6-tetramethyl-3,5-heptanedionate.

Neodymium alkoxides or aryloxides include neodymium methoxide, neodymiumethoxide, neodymium isopropoxide, neodymium 2-ethylhexoxide, neodymiumphenoxide, neodymium nonylphenoxide, and neodymium naphthoxide.

Neodymium halides include neodymium fluoride, neodymium chloride,neodymium bromide, and neodymium iodide. Suitable neodymiumpseudo-halides include neodymium cyanide, neodymium cyanate, neodymiumthiocyanate, neodymium azide, and neodymium ferrocyanide. Suitableneodymium oxyhalides include neodymium oxyfluoride, neodymiumoxychloride, and neodymium oxybromide. Where neodymium halides,neodymium oxyhalides, or other neodymium compounds containing labilehalogen atoms are employed, the neodymium-containing compound can alsoserve as the halogen-containing compound. A Lewis base such astetrahydrofuran (THF) may be employed as an aid for solubilizing thisclass of neodymium compounds in inert organic solvents.

The term “organolanthanide compound” may refer to any lanthanidecompound containing at least one lanthanide-carbon bond. These compoundsare predominantly, though not exclusively, those containingcyclopentadienyl (Cp), substituted cyclopentadienyl, allyl, andsubstituted allyl ligands. Suitable organolanthanide compounds includeCp₃Ln, Cp₂LnR, Cp₂LnCl, CpLnCl₂, CpLn(cyclooctatetraene), (C₅Me₅)₂LnR,LnR₃, Ln(allyl)₃, and Ln(allyl)₂Cl, where Ln represents a lanthanideatom, and R represents a hydrocarbyl group.

Various alkylating agents, or mixtures thereof, can be used. Alkylatingagents, which may also be referred to as hydrocarbylating agents,include organometallic compounds that can transfer hydrocarbyl groups toanother metal. Typically, these agents include organometallic compoundsof electropositive metals such as Groups 1, 2, and 3 metals (Groups IA,IIA, and IIIA metals). Where the alkylating agent includes a labilehalogen atom, the alkylating agent may also serve as thehalogen-containing compound. In one or more embodiments, alkylatingagents include organoaluminum and organomagnesium compounds.

The term “organoaluminum compound” may refer to any aluminum compoundcontaining at least one aluminum-carbon bond. In one or moreembodiments, organoaluminum compounds may be soluble in a hydrocarbonsolvent.

In one or more embodiments, organoaluminum compounds include thoserepresented by the formula AlR_(n)X_(3-n), where each R, which may bethe same or different, is a mono-valent organic group that is attachedto the aluminum atom via a carbon atom, where each X, which may be thesame or different, is a hydrogen atom, a halogen atom, a carboxylategroup, an alkoxide group, or an aryloxide group, and where n is aninteger of 1 to 3. In one or more embodiments, mono-valent organicgroups may include hydrocarbyl groups or substituted hydrocarbyl groupssuch as, but not limited to, alkyl, cycloalkyl, alkenyl, cycloalkenyl,aryl, allyl, aralkyl, alkaryl, or alkynyl groups. Substitutedhydrocarbyl groups include hydrocarbyl groups in which one or morehydrogen atoms have been replaced by a substituent such as an alkylgroup. These groups may also contain heteroatoms such as, but notlimited to, nitrogen, boron, oxygen, silicon, sulfur, tin, andphosphorus atoms.

Types of organoaluminum compounds represented by the formulaAlR_(n)X_(3-n) include trihydrocarbylaluminum, dihydrocarbylaluminumhydride, hydrocarbylaluminum dihydride, dihydrocarbylaluminumcarboxylate, hydrocarbylaluminum bis(carboxylate), dihydrocarbylaluminumalkoxide, hydrocarbylaluminum dialkoxide, dihydrocarbylaluminum halide,hydrocarbylaluminum dihalide, dihydrocarbylaluminum aryloxide, andhydrocarbylaluminum diaryloxide compounds.

Trihydrocarbylaluminum compounds include trimethylaluminum,triethylaluminum, triisobutylaluminum, tri-n-propylaluminum,triisopropylaluminum, tri-n-butylaluminum, tri-t-butylaluminum,tri-n-pentylaluminum, trineopentylaluminum, tri-n-hexylaluminum,tri-n-octylaluminum, tris(2-ethylhexyl) aluminum, tricyclohexylaluminum,tris(1-methylcyclopentyl) aluminum, triphenylaluminum,tri-p-tolylaluminum, tris(2,6-dimethylphenyl) aluminum,tribenzylaluminum, diethylphenylaluminum, diethyl-p-tolylaluminum,diethylbenzylaluminum, ethyldiphenylaluminum, ethyldi-p-tolylaluminum,and ethyldibenzylaluminum.

Dihydrocarbylaluminum hydride compounds include diethylaluminum hydride,di-n-propylaluminum hydride, diisopropylaluminum hydride,di-n-butylaluminum hydride, diisobutylaluminum hydride,di-n-octylaluminum hydride, diphenylaluminum hydride, di-p-tolylaluminumhydride, dibenzylaluminum hydride, phenylethylaluminum hydride,phenyl-n-propylaluminum hydride, phenylisopropylaluminum hydride,phenyl-n-butylaluminum hydride, phenylisobutylaluminum hydride,phenyl-n-octylaluminum hydride, p-tolylethylaluminum hydride,p-tolyl-n-propylaluminum hydride, p-tolylisopropylaluminum hydride,p-tolyl-n-butylaluminum hydride, p-tolylisobutylaluminum hydride,p-tolyl-n-octylaluminum hydride, benzylethylaluminum hydride,benzyl-n-propylaluminum hydride, benzylisopropylaluminum hydride,benzyl-n-butylaluminum hydride, benzylisobutylaluminum hydride, andbenzyl-n-octylaluminum hydride.

Hydrocarbylaluminum dihydride compounds include ethylaluminum dihydride,n-propylaluminum dihydride, isopropylaluminum dihydride, n-butylaluminumdihydride, isobutylaluminum dihydride, and n-octylaluminum dihydride.

Dihydrocarbylaluminum halide compounds include diethylaluminum chloride,di-n-propylaluminum chloride, diisopropylaluminum chloride,di-n-butylaluminum chloride, diisobutylaluminum chloride,di-n-octylaluminum chloride, diphenylaluminum chloride,di-p-tolylaluminum chloride, dibenzylaluminum chloride,phenylethylaluminum chloride, phenyl-n-propylaluminum chloride,phenylisopropylaluminum chloride, phenyl-n-butylaluminum chloride,phenylisobutylaluminum chloride, phenyl-n-octylaluminum chloride,p-tolylethylaluminum chloride, p-tolyl-n-propylaluminum chloride,p-tolylisopropylaluminum chloride, p-tolyl-n-butylaluminum chloride,p-tolylisobutylaluminum chloride, p-tolyl-n-octylaluminum chloride,benzylethylaluminum chloride, benzyl-n-propylaluminum chloride,benzylisopropylaluminum chloride, benzyl-n-butylaluminum chloride,benzylisobutylaluminum chloride, and benzyl-n-octylaluminum chloride.

Hydrocarbylaluminum dihalide compounds include ethylaluminum dichloride,n-propylaluminum dichloride, isopropylaluminum dichloride,n-butylaluminum dichloride, isobutylaluminum dichloride, andn-octylaluminum dichloride.

Other organoaluminum compounds represented by the formula AlR_(n)X_(3-n)include dimethylaluminum hexanoate, diethylaluminum octoate,diisobutylaluminum 2-ethylhexanoate, dimethylaluminum neodecanoate,diethylaluminum stearate, diisobutylaluminum oleate, methylaluminumbis(hexanoate), ethylaluminum bis(octoate), isobutylaluminumbis(2-ethylhexanoate), methylaluminum bis(neodecanoate), ethylaluminumbis(stearate), isobutylaluminum bis(oleate), dimethylaluminum methoxide,diethylaluminum methoxide, diisobutylaluminum methoxide,dimethylaluminum ethoxide, diethylaluminum ethoxide, diisobutylaluminumethoxide, dimethylaluminum phenoxide, diethylaluminum phenoxide,diisobutylaluminum phenoxide, methylaluminum dimethoxide, ethylaluminumdimethoxide, isobutylaluminum dimethoxide, methylaluminum diethoxide,ethylaluminum diethoxide, isobutylaluminum diethoxide, methylaluminumdiphenoxide, ethylaluminum diphenoxide, and isobutylaluminumdiphenoxide.

Another class of organoaluminum compounds include aluminoxanes.Aluminoxanes include oligomeric linear aluminoxanes that can berepresented by the general formula:

and oligomeric cyclic aluminoxanes that can be represented by thegeneral formula:

where x may be an integer of 1 to about 100, and in other embodimentsabout 10 to about 50; y may be an integer of 2 to about 100, and inother embodiments about 3 to about 20; and where each R, which may bethe same or different, may be a mono-valent organic group that isattached to the aluminum atom via a carbon atom. Mono-valent organicgroups are defined above. It should be noted that the number of moles ofthe aluminoxane as used in this application refers to the number ofmoles of the aluminum atoms rather than the number of moles of theoligomeric aluminoxane molecules. This convention is commonly employedin the art of catalysis utilizing aluminoxanes.

Aluminoxanes can be prepared by reacting trihydrocarbylaluminumcompounds with water. This reaction can be performed according to knownmethods, such as (1) a method in which the trihydrocarbylaluminumcompound may be dissolved in an organic solvent and then contacted withwater, (2) a method in which the trihydrocarbylaluminum compound may bereacted with water of crystallization contained in, for example, metalsalts, or water adsorbed in inorganic or organic compounds, and (3) amethod in which the trihydrocarbylaluminum compound may be reacted withwater in the presence of the monomer or monomer solution that is to bepolymerized.

Aluminoxane compounds include methylaluminoxane (MAO), modifiedmethylaluminoxane (MMAO), ethylaluminoxane, n-propylaluminoxane,isopropylaluminoxane, butylaluminoxane, isobutylaluminoxane,n-pentylaluminoxane, neopentylaluminoxane, n-hexylaluminoxane,n-octylaluminoxane, 2-ethylhexylaluminoxane, cyclohexylaluminoxane,1-methylcyclopentylaluminoxane, phenylaluminoxane, and2,6-dimethylphenylaluminoxane. Modified methylaluminoxane can be formedby substituting about 20-80% of the methyl groups of methylaluminoxanewith C₂ to C₁₂ hydrocarbyl groups, preferably with isobutyl groups, byusing techniques known to those skilled in the art.

Aluminoxanes can be used alone or in combination with otherorganoaluminum compounds. In one embodiment, methylaluminoxane and atleast one other organoaluminum compound (e.g., AlR_(n)X_(3-n)) such asdiisobutylaluminum hydride are employed in combination.

The term “organomagnesium compound” may refer to any magnesium compoundthat contains at least one magnesium-carbon bond. Organomagnesiumcompounds may be soluble in a hydrocarbon solvent.

One class of organomagnesium compounds that can be utilized may berepresented by the formula MgR₂, where each R, which may be the same ordifferent, is a mono-valent organic group that is attached to themagnesium atom via a carbon atom. In one or more embodiments,mono-valent organic groups may include hydrocarbyl groups or substitutedhydrocarbyl groups such as, but not limited to, alkyl, cycloalkyl,alkenyl, cycloalkenyl, aryl, allyl, aralkyl, alkaryl, or alkynyl groups.These groups may contain heteroatoms such as, but not limited to,nitrogen, boron, oxygen, silicon, sulfur, tin, and phosphorus atoms.

Specific examples of organomagnesium compounds represented by theformula MgR₂ include diethylmagnesium, di-n-propylmagnesium,diisopropylmagnesium, dibutylmagnesium, dihexylmagnesium,diphenylmagnesium, and dibenzylmagnesium.

Another class of organomagnesium compounds that can be utilized includethose that may be represented by the formula RMgX, where R is amono-valent organic group that is attached to the magnesium atom via acarbon atom, and X is a hydrogen atom, a halogen atom, a carboxylategroup, an alkoxide group, or an aryloxide group. Mono-valent organicgroups are defined above. In one or more embodiments, X is a carboxylategroup, an alkoxide group, or an aryloxide group.

Exemplary types of organomagnesium compounds represented by the formulaRMgX include hydrocarbylmagnesium hydride, hydrocarbylmagnesium halide,hydrocarbylmagnesium carboxylate, hydrocarbylmagnesium alkoxide, andhydrocarbylmagnesium aryloxide.

Specific examples of organomagnesium compounds represented by theformula RMgX include methylmagnesium hydride, ethylmagnesium hydride,butylmagnesium hydride, hexylmagnesium hydride, phenylmagnesium hydride,benzylmagnesium hydride, methylmagnesium chloride, ethylmagnesiumchloride, butylmagnesium chloride, hexylmagnesium chloride,phenylmagnesium chloride, benzylmagnesium chloride, methylmagnesiumbromide, ethylmagnesium bromide, butylmagnesium bromide, hexylmagnesiumbromide, phenylmagnesium bromide, benzylmagnesium bromide,methylmagnesium hexanoate, ethylmagnesium hexanoate, butylmagnesiumhexanoate, hexylmagnesium hexanoate, phenylmagnesium hexanoate,benzylmagnesium hexanoate, methylmagnesium ethoxide, ethylmagnesiumethoxide, butylmagnesium ethoxide, hexylmagnesium ethoxide,phenylmagnesium ethoxide, benzylmagnesium ethoxide, methylmagnesiumphenoxide, ethylmagnesium phenoxide, butylmagnesium phenoxide,hexylmagnesium phenoxide, phenylmagnesium phenoxide, and benzylmagnesiumphenoxide.

Various halogen-containing compounds, or mixtures thereof, that containone or more labile halogen atoms can be employed. Examples of halogenatoms include, but are not limited to, fluorine, chlorine, bromine, andiodine. A combination of two or more halogen-containing compounds havingdifferent halogen atoms can also be utilized. In one or moreembodiments, the halogen-containing compounds may be soluble in ahydrocarbon solvent. In other embodiments, hydrocarbon-insolublehalogen-containing compounds, which can be suspended in thepolymerization medium to form the catalytically active species, may beuseful.

Suitable types of halogen-containing compounds include elementalhalogens, mixed halogens, hydrogen halides, organic halides, inorganichalides, metallic halides, and organometallic halides.

Elemental halogens include fluorine, chlorine, bromine, and iodine.Mixed halogens include iodine monochloride, iodine monobromide, iodinetrichloride, and iodine pentafluoride.

Hydrogen halides include hydrogen fluoride, hydrogen chloride, hydrogenbromide, and hydrogen iodide.

Organic halides include t-butyl chloride, t-butyl bromides, t-butyliodide, allyl chloride, allyl bromide, allyl iodide, carbontetrachloride, carbon tetrabromide, carbon tetraiodide, chloroform,bromoform, iodoform, benzyl chloride, benzyl bromide, benzyl iodide,diphenylmethyl chloride, diphenylmethyl bromide, triphenylmethylchloride, triphenylmethyl bromide, benzylidene chloride, benzylidenebromide, methyltrichlorosilane, phenyltrichlorosilane,dimethyldichlorosilane, diphenyldichlorosilane, trimethylsilyl chloride,trimethylsilyl bromide, trimethylsilyl iodide, benzoyl chloride, benzoylbromide, propionyl chloride, propionyl bromide, methyl chloroformate,and methyl bromoformate.

Inorganic halides include phosphorus trichloride, phosphorus tribromide,phosphorus triiodide, phosphorus pentachloride, phosphorus oxychloride,phosphorus oxybromide, boron trifluoride, boron trichloride, borontribromide, silicon tetrafluoride, silicon tetrachloride, silicontetrabromide, silicon tetraiodide, arsenic trichloride, arsenictribromide, arsenic triiodide, selenium tetrachloride, seleniumtetrabromide, tellurium tetrachloride, tellurium tetrabromide, andtellurium tetraiodide.

Metallic halides include tin tetrachloride, tin tetrabromide, tintetraiodide, aluminum trichloride, aluminum tribromide, antimonytrichloride, antimony pentachloride, antimony tribromide, aluminumtriiodide, aluminum trifluoride, gallium trichloride, galliumtribromide, gallium triiodide, gallium trifluoride, indium trichloride,indium tribromide, indium triiodide, indium trifluoride, titaniumtetrachloride, titanium tetrabromide, titanium tetraiodide, zincdichloride, zinc dibromide, zinc diiodide, and zinc difluoride.

Organometallic halides include dimethylaluminum chloride,diethylaluminum chloride, diisobutylaluminum chloride, dimethylaluminumbromide, diethylaluminum bromide, diisobutylaluminum bromide,dimethylaluminum fluoride, diethylaluminum fluoride, diisobutylaluminumfluoride, dimethylaluminum iodide, diethylaluminum iodide,diisobutylaluminum iodide, methylaluminum dichloride, ethylaluminumdichloride, methylaluminum dibromide, ethylaluminum dibromide,methylaluminum difluoride, ethylaluminum difluoride, methylaluminumsesquichloride, ethylaluminum sesquichloride, isobutylaluminumsesquichloride, methylmagnesium chloride, methylmagnesium bromide,methylmagnesium iodide, ethylmagnesium chloride, ethylmagnesium bromide,butylmagnesium chloride, butylmagnesium bromide, phenylmagnesiumchloride, phenylmagnesium bromide, benzylmagnesium chloride,trimethyltin chloride, trimethyltin bromide, triethyltin chloride,triethyltin bromide, di-t-butyltin dichloride, di-t-butyltin dibromide,dibutyltin dichloride, dibutyltin dibromide, tributyltin chloride, andtributyltin bromide.

Compounds containing non-coordinating anions are known in the art. Ingeneral, non-coordinating anions are sterically bulky anions that do notform coordinate bonds with, for example, the active center of a catalystsystem due to steric hindrance. Exemplary non-coordinating anionsinclude tetraarylborate anions and fluorinated tetraarylborate anions.Compounds containing a non-coordinating anion also contain a countercation such as a carbonium, ammonium, or phosphonium cation. Exemplarycounter cations include triarylcarbonium cations andN,N-dialkylanilinium cations. Examples of compounds containing anon-coordinating anion and a counter cation include triphenylcarboniumtetrakis(pentafluorophenyl) borate, N,N-dimethylaniliniumtetrakis(pentafluorophenyl) borate, triphenylcarboniumtetrakis[3,5-bis(trifluoromethyl)phenyl]borate, andN,N-dimethylanilinium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate.

Non-coordinating anion precursors include compounds that can form anon-coordinating anion under reaction conditions. Exemplarynon-coordinating anion precursors include triarylboron compounds, BR₃,where R is a strong electron-withdrawing aryl group such as apentafluorophenyl or 3,5-bis(trifluoromethyl)phenyl group.

The lanthanide-based catalyst composition used in this invention may beformed by combining or mixing the foregoing catalyst ingredients.Although one or more active catalyst species are believed to result fromthe combination of the lanthanide-based catalyst ingredients, the degreeof interaction or reaction between the various catalyst ingredients orcomponents is not known with any great degree of certainty. Therefore,the term “catalyst composition” has been employed to encompass a simplemixture of the ingredients, a complex of the various ingredients that iscaused by physical or chemical forces of attraction, a chemical reactionproduct of the ingredients, or a combination of the foregoing.

The foregoing lanthanide-based catalyst composition may have highcatalytic activity for polymerizing conjugated dienes intocis-1,4-polydienes over a wide range of catalyst concentrations andcatalyst ingredient ratios. Several factors may impact the optimumconcentration of any one of the catalyst ingredients. For example,because the catalyst ingredients may interact to form an active species,the optimum concentration for any one catalyst ingredient may bedependent upon the concentrations of the other catalyst ingredients.

In one or more embodiments, the molar ratio of the alkylating agent tothe lanthanide compound (alkylating agent/Ln) can be varied from about1:1 to about 1,000:1, in other embodiments from about 2:1 to about500:1, and in other embodiments from about 5:1 to about 200:1.

In those embodiments where both an aluminoxane and at least one otherorganoaluminum agent are employed as alkylating agents, the molar ratioof the aluminoxane to the lanthanide compound (aluminoxane/Ln) can bevaried from 5:1 to about 1,000:1, in other embodiments from about 10:1to about 700:1, and in other embodiments from about 20:1 to about 500:1;and the molar ratio of the at least one other organoaluminum compound tothe lanthanide compound (Al/Ln) can be varied from about 1:1 to about200:1, in other embodiments from about 2:1 to about 150:1, and in otherembodiments from about 5:1 to about 100:1.

The molar ratio of the halogen-containing compound to the lanthanidecompound is best described in terms of the ratio of the moles of halogenatoms in the halogen-containing compound to the moles of lanthanideatoms in the lanthanide compound (halogen/Ln). In one or moreembodiments, the halogen/Ln molar ratio can be varied from about 0.5:1to about 20:1, in other embodiments from about 1:1 to about 10:1, and inother embodiments from about 2:1 to about 6:1.

In yet another embodiment, the molar ratio of the non-coordinating anionor non-coordinating anion precursor to the lanthanide compound (An/Ln)may be from about 0.5:1 to about 20:1, in other embodiments from about0.75:1 to about 10:1, and in other embodiments from about 1:1 to about6:1.

The lanthanide-based catalyst composition can be formed by variousmethods.

In one embodiment, the lanthanide-based catalyst composition may beformed in situ by adding the catalyst ingredients to a solutioncontaining monomer and solvent, or to bulk monomer, in either a stepwiseor simultaneous manner. In one embodiment, the alkylating agent can beadded first, followed by the lanthanide compound, and then followed bythe halogen-containing compound, if used, or by the compound containinga non-coordinating anion or the non-coordinating anion precursor.

In another embodiment, the lanthanide-based catalyst composition may bepreformed. That is, the catalyst ingredients are pre-mixed outside thepolymerization system either in the absence of any monomer or in thepresence of a small amount of at least one conjugated diene monomer atan appropriate temperature, which may be from about −20° C. to about 80°C. The amount of conjugated diene monomer that may be used forpreforming the catalyst can range from about 1 to about 500 moles, inother embodiments from about 5 to about 250 moles, and in otherembodiments from about 10 to about 100 moles per mole of the lanthanidecompound. The resulting catalyst composition may be aged, if desired,prior to being added to the monomer that is to be polymerized.

In yet another embodiment, the lanthanide-based catalyst composition maybe formed by using a two-stage procedure. The first stage may involvecombining the alkylating agent with the lanthanide compound either inthe absence of any monomer or in the presence of a small amount of atleast one conjugated diene monomer at an appropriate temperature, whichmay be from about −20° C. to about 80° C. The amount of monomer employedin the first stage may be similar to that set forth above for performingthe catalyst. In the second stage, the mixture formed in the first stageand the halogen-containing compound, non-coordinating anion, ornon-coordinating anion precursor can be charged in either a stepwise orsimultaneous manner to the monomer that is to be polymerized.

In one or more embodiments, a solvent may be employed as a carrier toeither dissolve or suspend the catalyst in order to facilitate thedelivery of the catalyst to the polymerization system. In otherembodiments, monomer can be used as the carrier. In yet otherembodiments, the catalyst can be used in their neat state without anysolvent.

In one or more embodiments, suitable solvents include those organiccompounds that will not undergo polymerization or incorporation intopropagating polymer chains during the polymerization of monomer in thepresence of the catalyst. In one or more embodiments, these organicspecies are liquid at ambient temperature and pressure. In one or moreembodiments, these organic solvents are inert to the catalyst. Exemplaryorganic solvents include hydrocarbons with a low or relatively lowboiling point such as aromatic hydrocarbons, aliphatic hydrocarbons, andcycloaliphatic hydrocarbons. Non-limiting examples of aromatichydrocarbons include benzene, toluene, xylenes, ethylbenzene,diethylbenzene, and mesitylene. Non-limiting examples of aliphatichydrocarbons include n-pentane, n-hexane, n-heptane, n-octane, n-nonane,n-decane, isopentane, isohexanes, isopentanes, isooctanes,2,2-dimethylbutane, petroleum ether, kerosene, and petroleum spirits.And, non-limiting examples of cycloaliphatic hydrocarbons includecyclopentane, cyclohexane, methylcyclopentane, and methylcyclohexane.Mixtures of the above hydrocarbons may also be used. As is known in theart, aliphatic and cycloaliphatic hydrocarbons may be desirably employedfor environmental reasons. The low-boiling hydrocarbon solvents aretypically separated from the polymer upon completion of thepolymerization.

Other examples of organic solvents include high-boiling hydrocarbons ofhigh molecular weights, such as paraffinic oil, aromatic oil, or otherhydrocarbon oils that are commonly used to oil-extend polymers. Sincethese hydrocarbons are non-volatile, they typically do not requireseparation and remain incorporated in the polymer.

The production of the reactive polymer according to this invention canbe accomplished by polymerizing conjugated diene monomer in the presenceof a catalytically effective amount of the coordination catalyst. Theintroduction of the catalyst, the conjugated diene monomer, and anysolvent, if employed, forms a polymerization mixture in which thereactive polymer is formed. The amount of the catalyst to be employedmay depend on the interplay of various factors such as the type ofcatalyst employed, the purity of the ingredients, the polymerizationtemperature, the polymerization rate and conversion desired, themolecular weight desired, and many other factors. Accordingly, aspecific catalyst amount cannot be definitively set forth except to saythat catalytically effective amounts of the catalyst may be used.

In one or more embodiments, the amount of the coordinating metalcompound (e.g., a lanthanide compound) used can be varied from about0.001 to about 2 mmol, in other embodiments from about 0.005 to about 1mmol, and in still other embodiments from about 0.01 to about 0.2 mmolper 100 gram of monomer.

In one or more embodiments, the polymerization may be carried out in apolymerization system that includes a substantial amount of solvent. Inone embodiment, a solution polymerization system may be employed inwhich both the monomer to be polymerized and the polymer formed aresoluble in the solvent. In another embodiment, a precipitationpolymerization system may be employed by choosing a solvent in which thepolymer formed is insoluble. In both cases, an amount of solvent inaddition to the amount of solvent that may be used in preparing thecatalyst is usually added to the polymerization system. The additionalsolvent may be the same as or different from the solvent used inpreparing the catalyst. Exemplary solvents have been set forth above. Inone or more embodiments, the solvent content of the polymerizationmixture may be more than 20% by weight, in other embodiments more than50% by weight, and in still other embodiments more than 80% by weightbased on the total weight of the polymerization mixture.

In other embodiments, the polymerization system employed may begenerally considered a bulk polymerization system that includessubstantially no solvent or a minimal amount of solvent. Those skilledin the art will appreciate the benefits of bulk polymerization processes(i.e., processes where monomer acts as the solvent), and therefore thepolymerization system includes less solvent than will deleteriouslyimpact the benefits sought by conducting bulk polymerization. In one ormore embodiments, the solvent content of the polymerization mixture maybe less than about 20% by weight, in other embodiments less than about10% by weight, and in still other embodiments less than about 5% byweight based on the total weight of the polymerization mixture. Inanother embodiment, the polymerization mixture contains no solventsother than those that are inherent to the raw materials employed. Instill another embodiment, the polymerization mixture is substantiallydevoid of solvent, which refers to the absence of that amount of solventthat would otherwise have an appreciable impact on the polymerizationprocess. Polymerization systems that are substantially devoid of solventmay be referred to as including substantially no solvent. In particularembodiments, the polymerization mixture is devoid of solvent.

The polymerization may be conducted in any conventional polymerizationvessels known in the art. In one or more embodiments, solutionpolymerization can be conducted in a conventional stirred-tank reactor.In other embodiments, bulk polymerization can be conducted in aconventional stirred-tank reactor, especially if the monomer conversionis less than about 60%. In still other embodiments, especially where themonomer conversion in a bulk polymerization process is higher than about60%, which typically results in a highly viscous cement, the bulkpolymerization may be conducted in an elongated reactor in which theviscous cement under polymerization is driven to move by piston, orsubstantially by piston. For example, extruders in which the cement ispushed along by a self-cleaning single-screw or double-screw agitatorare suitable for this purpose. Examples of useful bulk polymerizationprocesses are disclosed in U.S. Pat. No. 7,351,776, which isincorporated herein by reference.

In one or more embodiments, all of the ingredients used for thepolymerization can be combined within a single vessel (e.g., aconventional stirred-tank reactor), and all steps of the polymerizationprocess can be conducted within this vessel. In other embodiments, twoor more of the ingredients can be pre-combined in one vessel and thentransferred to another vessel where the polymerization of monomer (or atleast a major portion thereof) may be conducted.

The polymerization can be carried out as a batch process, a continuousprocess, or a semi-continuous process. In the semi-continuous process,the monomer is intermittently charged as needed to replace that monomeralready polymerized. In one or more embodiments, the conditions underwhich the polymerization proceeds may be controlled to maintain thetemperature of the polymerization mixture within a range from about −10°C. to about 200° C., in other embodiments from about 0° C. to about 150°C., and in other embodiments from about 20° C. to about 100° C. In oneor more embodiments, the heat of polymerization may be removed byexternal cooling by a thermally controlled reactor jacket, internalcooling by evaporation and condensation of the monomer through the useof a reflux condenser connected to the reactor, or a combination of thetwo methods. Also, the polymerization conditions may be controlled toconduct the polymerization under a pressure of from about 0.1 atmosphereto about 50 atmospheres, in other embodiments from about 0.5 atmosphereto about 20 atmosphere, and in other embodiments from about 1 atmosphereto about 10 atmospheres. In one or more embodiments, the pressures atwhich the polymerization may be carried out include those that ensurethat the majority of the monomer is in the liquid phase. In these orother embodiments, the polymerization mixture may be maintained underanaerobic conditions.

Some or all of the resulting polymer chains may possess reactive endsbefore the polymerization mixture is quenched. As noted above, thereactive polymer prepared with a coordination catalyst may be referredto as a pseudo-living polymer. In one or more embodiments, apolymerization mixture including reactive polymer may be referred to asan active polymerization mixture. The percentage of polymer chainspossessing a reactive end depends on various factors such as the type ofcatalyst, the type of monomer, the purity of the ingredients, thepolymerization temperature, the monomer conversion, and many otherfactors. In one or more embodiments, at least about 20% of the polymerchains possess a reactive end, in other embodiments at least about 50%of the polymer chains possess a reactive end, and in still otherembodiments at least about 80% of the polymer chains possess a reactiveend. In any event, the reactive polymer can be reacted with nitrosocompounds to form the functionalized polymer of this invention.

In one or more embodiments, nitroso compounds include those compoundsthat contain at least one nitroso group, which may be defined by theformula —N═O. In one or more embodiments, the nitroso compounds may bedefined by the formula β—N═0, where β is a mono-valent organic group.

The nitroso compounds may be classified accordingly to the type of themono-valent organic group β attached to the nitroso group. In one ormore embodiments, the β group may be an aliphatic group, acycloaliphatic group, an aromatic group, or a heterocyclic group.Accordingly, the corresponding nitroso compound may be referred to as analiphatic, cycloaliphatic, aromatic, or heterocyclic nitroso compound.In those embodiments where the β group is an cycloaliphatic group, anaromatic group, or a heterocyclic group, the β group may be monocyclic,bicyclic, tricyclic, or multicyclic. In those embodiments where the βgroup is a heterocyclic group, the β group may be aromatic ornon-aromatic, may be saturated or unsaturated, and may contain oneheteroatom or multiple heteroatoms that are either the same or distinct.In particular embodiments, the heteroatoms may be selected from thegroup consisting of nitrogen, oxygen, sulfur, boron, silicon, tin, andphosphorus atoms.

The nitroso compounds may also be classified accordingly to the type ofatom attached to the nitroso group. In one or more embodiments, the βgroup may be bonded to the nitroso group through a carbon atom, anitrogen atom, an oxygen atom, or a sulfur atom that resides within theβ group. Depending on the type of atom (e.g., C, N, O, or S atom)through which the β group is bonded to the nitroso group, thecorresponding nitroso compounds may be referred to as C-nitroso,N-nitroso, O-nitroso, and S-nitroso compounds, respectively. In one ormore embodiments, the remaining substituents or groups attached to the Cor N atom may be mono-valent or divalent. In one or more embodiments,the remaining substituents or groups attached to the O or S atom ismono-valent.

In those embodiments where the β group is bonded to the nitroso groupthrough a carbon atom, the β group may be a hydrocarbyl group orsubstituted hydrocarbyl group. In one or more embodiments, hydrocarbylgroups or substituted hydrocarbyl groups may include, but are notlimited to, alkyl, cycloalkyl, alkenyl, cycloalkenyl, aryl, allyl,aralkyl, alkaryl, or alkynyl groups. Substituted hydrocarbyl groupsinclude hydrocarbyl groups in which one or more hydrogen atoms have beenreplaced by a substituent such as an alkyl group. In one or moreembodiments, these groups may include from one, or the appropriateminimum number of carbon atoms to form the group, to 20 carbon atoms.These groups may also contain heteroatoms such as, but not limited to,nitrogen, boron, oxygen, silicon, sulfur, tin, and phosphorus atoms.

In those embodiments where the β group is bonded to the nitroso groupthrough a nitrogen atom, the β group may be a protected amino group. Inone or more embodiments, protected amino groups include those aminogroups that are formed or derived by replacing the two acidic hydrogenatoms of the parent amino group (i.e. —NH₂) with substituents such ashydrocarbyl or silyl groups. Exemplary types of protected amino groupsinclude, but are not limited to, bis(trihydrocarbylsilyl)amino,bis(dihydrocarbylhydrosilyl)amino, 1-aza-disila-1-cyclohydrocarbyl,(trihydrocarbylsilyl) (hydrocarbyl)amino, (dihydrocarbylhydrosilyl)(hydrocarbyl)amino, 1-aza-2-sila-1-cyclohydrocarbyl, dihydrocarbylamino,and 1-aza-1-cyclohydrocarbyl groups.

In those embodiments where the β group is bonded to the nitroso groupthrough an oxygen atom, the β group may be a hydrocarbyloxy group orsubstituted hydrocarbyloxy group. In one or more embodiments,hydrocarbyloxy groups or substituted hydrocarbyloxy groups may include,but are not limited to, alkoxy, cycloalkoxy, alkenoxy, cycloalkenoxy,aryloxy, allyloxy, aralkoxy, alkaryloxy, or alkynoxy groups. Substitutedhydrocarbyloxy groups include hydrocarbyloxy groups in which one or morehydrogen atoms have been replaced by a substituent such as an alkylgroup. In one or more embodiments, these groups may include from one, orthe appropriate minimum number of carbon atoms to form the group, to 20carbon atoms. These groups may also contain heteroatoms such as, but notlimited to, nitrogen, boron, oxygen, silicon, sulfur, tin, andphosphorus atoms.

In those embodiments where the β group is bonded to the nitroso groupthrough a sulfur atom, the β group may be a hydrocarbylthio group orsubstituted hydrocarbylthio group. In one or more embodiments,hydrocarbylthio groups or substituted hydrocarbylthio groups include,but are not limited to, alkylthio, cycloalkylthio, alkenylthio,cycloalkenylthio, arylthio, allylthio, aralkylthio, alkarylthio, oralkynylthio groups. Substituted hydrocarbylthio groups includehydrocarbylthio groups in which one or more hydrogen atoms have beenreplaced by a substituent such as an alkyl group. In one or moreembodiments, these groups may include from one, or the appropriateminimum number of carbon atoms to form the group, to 20 carbon atoms.These groups may also contain heteroatoms such as, but not limited to,nitrogen, boron, oxygen, silicon, sulfur, tin, and phosphorus atoms.

Examples of C-nitroso compounds include, but are not limited to,nitrosomethane, nitrosoethane, 1-nitroso-n-propane, 2-nitroso-n-propane,1-nitroso-n-butane, 2-methyl-2-nitrosopropane, 1-nitroso-n-pentane,1-nitroso-n-hexane, 1-nitroso-n-heptane, 1-nitroso-n-octane,1-nitroso-n-nonane, 1-nitroso-n-decane, 1-nitroso-n-dodecane,nitrosocyclopentane, nitrosocyclohexane, nitrosocyclooctane,nitrosobenzene, 2-nitrosotoluene, 3-nitrosotoluene, 4-nitrosotoluene,N,N-dimethyl-4-nitrosoaniline, N,N-diethyl-4-nitrosoaniline,2-nitrosopyridine, 3-nitrosopyridine, 4-nitrosopyridine,nitrosopyrazine, 2-nitrosopyrimidine, 4-nitrosopyrimidine,5-nitrosopyrimidine, 3-nitrosopyridazine, 4-nitrosopyridazine,2-nitrosoquinoline, 3-nitrosoquinoline, 4-nitrosoquinoline,1-nitrosophthalazine, 2-nitrosoquinazoline, 4-nitrosoquinazoline,2-nitrosoquinoxaline, 2-nitroso-1,10-phenanthroline,3-nitroso-1,10-phenanthroline, 4-nitroso-1,10-phenanthroline,5-nitroso-1,10-phenanthroline, 1-nitrosophenazine, 2-nitrosophenazine,N-methyl-2-nitrosopyrrolidine, N-methyl-2-nitrosopyrrole,N-methyl-3-nitrosopyrrole, N-methyl-2-nitrosoimidazole,N-methyl-4-nitrosoimidazole, N-methyl-5-nitrosoimidazole,N-methyl-3-nitrosopyrazole, N-methyl-4-nitrosopyrazole,N-methyl-5-nitrosopyrazole, N-methyl-2-nitrosopiperidine,N-methyl-2-nitrosohomopiperidine, N-methyl-2-nitrosomorpholine,N-(trimethylsilyl)-2-nitrosopyrrolidine,N-(trimethylsilyl)-2-nitrosopyrrole,N-(trimethylsilyl)-3-nitrosopyrrole,N-(trimethylsilyl)-2-nitrosoimidazole,N-(trimethylsilyl)-4-nitrosoimidazole,N-(trimethylsilyl)-5-nitrosoimidazole,N-(trimethylsilyl)-3-nitrosopyrazole,N-(trimethylsilyl)-4-nitrosopyrazole,N-(trimethylsilyl)-5-nitrosopyrazole,N-(trimethylsilyl)-2-nitrosopiperidine,N-(trimethylsilyl)-2-nitrosohomopiperidine, andN-(trimethylsilyl)-2-nitrosomorpholine.

Examples of N-nitroso compounds include, but are not limited toN-nitrosopyrrolidine, N-nitrosopyrrole, N-nitrosoimidazole,N-nitrosopyrazole, N-nitrosopiperidine, N-nitrosohomopiperidine,N-nitrosomorpholine, N-nitrosonornicotine, N-nitrosodimethylamine,N-nitrosodiethylamine, N-nitrosodi-n-propylamine,N-nitrosodiisopropylamine N-nitrosodi-n-butylamine,N-nitrosodiisobutylamine, N-nitrosodi-t-butylamine,N-nitrosodineopentylamine, N-nitrosodiphenylamine,N-nitrosodibenzylamine, N-nitrosodi-2-tolylamine,N-nitrosodi-3-tolylamine, N-nitrosodi-4-tolylamine,N-nitrosodi-2-pyridylamine, N-benzyl-N-nitroso-p-toluenesulfonamide,N-nitrosobis(trimethylsilyl)amine, N-nitrosobis(triethylsilyl)amine,N-nitrosobis(triisopropylsilyl)amine, N-nitrosobis(triphenylsilyl)amine,and N-nitroso(trimethylsilyl)(methyl)amine.

Examples of O-nitroso compounds, which may also be referred to asnitrite compounds, include, but are not limited to, methyl nitrite,ethyl nitrite, n-propyl nitrite, isopropyl nitrite, n-butyl nitrite,isobutyl nitrite, t-butyl nitrite, neopentyl nitrite, benzyl nitrite,phenyl nitrite, trimethylsilyl nitrite, triethylsilyl nitrite,triisopropylsilyl nitrite, and triphenylsilyl nitrite.

Examples of S-nitroso compounds, which may also be referred to asthionitrite compounds, include, but are not limited to, methylthionitrite, ethyl thionitrite, n-propyl thionitrite, isopropylthionitrite, n-butyl thionitrite, isobutyl thionitrite, t-butylthionitrite, neopentyl thionitrite, benzyl thionitrite, phenylthionitrite trimethylsilyl thionitrite, triethylsilyl thionitrite,triisopropylsilyl thionitrite, and triphenylsilyl thionitrite.

The amount of the nitroso compound that can be added to thepolymerization mixture may depend on various factors including the typeand amount of catalyst used to synthesize the reactive polymer and thedesired degree of functionalization. In one or more embodiments, wherethe reactive polymer is prepared by employing a lanthanide-basedcatalyst, the amount of the nitroso compound employed can be describedwith reference to the lanthanide metal of the lanthanide compound. Forexample, the molar ratio of the nitroso compound to the lanthanide metalmay be from about 1:1 to about 200:1, in other embodiments from about5:1 to about 150:1, and in other embodiments from about 10:1 to about100:1.

In one or more embodiments, in addition to the nitroso compound, aco-functionalizing agent may also be added to the polymerization mixtureto yield a functionalized polymer with tailored properties. A mixture oftwo or more co-functionalizing agents may also be employed. Theco-functionalizing agent may be added to the polymerization mixtureprior to, together with, or after the introduction of the nitrosocompound. In one or more embodiments, the co-functionalizing agent isadded to the polymerization mixture at least 5 minutes after, in otherembodiments at least 10 minutes after, and in other embodiments at least30 minutes after the introduction of the nitroso compound.

In one or more embodiments, co-functionalizing agents include compoundsor reagents that can react with a reactive polymer produced by thisinvention and thereby provide the polymer with a functional group thatis distinct from a propagating chain that has not been reacted with theco-functionalizing agent. The functional group may be reactive orinteractive with other polymer chains (propagating and/ornon-propagating) or with other constituents such as reinforcing fillers(e.g. carbon black) that may be combined with the polymer. In one ormore embodiments, the reaction between the co-functionalizing agent andthe reactive polymer proceeds via an addition or substitution reaction.

Useful co-functionalizing agents may include compounds that simplyprovide a functional group at the end of a polymer chain without joiningtwo or more polymer chains together, as well as compounds that cancouple or join two or more polymer chains together via a functionallinkage to form a single macromolecule. The latter type ofco-functionalizing agents may also be referred to as coupling agents.

In one or more embodiments, co-functionalizing agents include compoundsthat will add or impart a heteroatom to the polymer chain. In particularembodiments, co-functionalizing agents include those compounds that willimpart a functional group to the polymer chain to form a functionalizedpolymer that reduces the 50° C. hysteresis loss of a carbon-black filledvulcanizates prepared from the functionalized polymer as compared tosimilar carbon-black filled vulcanizates prepared fromnon-functionalized polymer. In one or more embodiments, this reductionin hysteresis loss is at least 5%, in other embodiments at least 10%,and in other embodiments at least 15%.

In one or more embodiments, suitable co-functionalizing agents includethose compounds that contain groups that may react with the reactivepolymers produced in accordance with this invention. Exemplaryco-functionalizing agents include ketones, quinones, aldehydes, amides,esters, isocyanates, isothiocyanates, epoxides, imines, aminoketones,aminothioketones, and acid anhydrides. Examples of these compounds aredisclosed in U.S. Pat. Nos. 4,906,706, 4,990,573, 5,064,910, 5,567,784,5,844,050, 6838,526, 6977,281, and 6,992,147; U.S. Pat. Publication Nos.2006/0004131 A1, 2006/0025539 A1, 2006/0030677 A1, and 2004/0147694 A1;Japanese Patent Application Nos. 05-051406A, 05-059103A, 10-306113A, and11-035633A; which are incorporated herein by reference. Other examplesof co-functionalizing agents include azine compounds as described inU.S. Ser. No. 11/640,711, hydrobenzamide compounds as disclosed in U.S.Ser. No. 11/710,713, nitro compounds as disclosed in U.S. Ser. No.11/710,845, and protected oxime compounds as disclosed in U.S. Ser. No.60/875,484, all of which are incorporated herein by reference.

In particular embodiments, the co-functionalizing agents employed may bemetal halides, metalloid halides, alkoxysilanes, metal carboxylates,hydrocarbylmetal carboxylates, hydrocarbylmetal ester-carboxylates, andmetal alkoxides.

Exemplary metal halide compounds include tin tetrachloride, tintetrabromide, tin tetraiodide, n-butyltin trichloride, phenyltintrichloride, di-n-butyltin dichloride, diphenyltin dichloride,tri-n-butyltin chloride, triphenyltin chloride, germanium tetrachloride,germanium tetrabromide, germanium tetraiodide, n-butylgermaniumtrichloride, di-n-butylgermanium dichloride, and tri-n-butylgermaniumchloride.

Exemplary metalloid halide compounds include silicon tetrachloride,silicon tetrabromide, silicon tetraiodide, methyltrichlorosilane,phenyltrichlorosilane, dimethyldichlorosilane, diphenyldichlorosilane,boron trichloride, boron tribromide, boron triiodide, phosphoroustrichloride, phosphorous tribromide, and phosphorus triiodide.

In one or more embodiments, the alkoxysilanes may include at least onegroup selected from the group consisting of an epoxy group and anisocyanate group.

Exemplary alkoxysilane compounds including an epoxy group include(3-glycidyloxypropyl)trimethoxysilane,(3-glycidyloxypropyl)triethoxysilane,(3-glycidyloxypropyl)triphenoxysilane,(3-glycidyloxypropyl)methyldimethoxysilane,(3-glycidyloxypropyl)methyldiethoxysilane,(3-glycidyloxypropyl)methyldiphenoxysilane,[2-(3,4-epoxycyclohexyl)ethyl]trimethoxysilane, and[2-(3,4-epoxycyclohexyl)ethyl]triethoxysilane,

Exemplary alkoxysilane compounds including an isocyanate group include(3-isocyanatopropyl)trimethoxysilane,(3-isocyanatopropyl)triethoxysilane,(3-isocyanatopropyl)triphenoxysilane,(3-isocyanatopropyl)methyldimethoxysilane,(3-isocyanatopropyl)methyldiethoxysilane(3-isocyanatopropyl)methyldiphenoxysilane, and(isocyanatomethyl)methyldimethoxysilane.

Exemplary metal carboxylate compounds include tin tetraacetate, tinbis(2-ethylhexanaote), and tin bis(neodecanoate).

Exemplary hydrocarbylmetal carboxylate compounds include triphenyltin2-ethylhexanoate, tri-n-butyltin 2-ethylhexanoate, tri-n-butyltinneodecanoate, triisobutyltin 2-ethylhexanoate, diphenyltinbis(2-ethylhexanoate), di-n-butyltin bis(2-ethylhexanoate),di-n-butyltin bis(neodecanoate), phenyltin tris(2-ethylhexanoate), andn-butylltin tris(2-ethylhexanoate).

Exemplary hydrocarbylmetal ester-carboxylate compounds includedi-n-butyltin bis(n-octylmaleate), di-n-octyltin bis(n-octylmaleate),diphenyltin bis(n-octylmaleate), di-n-butyltin bis(2-ethylhexylmaleate),di-n-octyltin bis(2-ethylhexylmaleate), and diphenyltinbis(2-ethylhexylmaleate).

Exemplary metal alkoxide compounds include dimethoxytin, diethoxytin,tetraethoxytin, tetra-n-propoxytin, tetraisopropoxytin,tetra-n-butoxytin, tetraisobutoxytin, tetra-t-butoxytin, andtetraphenoxytin.

The amount of the co-functionalizing agent that can be added to thepolymerization mixture may depend on various factors including the typeand amount of catalyst used to synthesize the reactive polymer and thedesired degree of functionalization. In one or more embodiments, wherethe reactive polymer is prepared by employing a lanthanide-basedcatalyst, the amount of the co-functionalizing agent employed can bedescribed with reference to the lanthanide metal of the lanthanidecompound. For example, the molar ratio of the co-functionalizing agentto the lanthanide metal may be from about 1:1 to about 200:1, in otherembodiments from about 5:1 to about 150:1, and in other embodiments fromabout 10:1 to about 100:1.

The amount of the co-functionalizing agent employed can also bedescribed with reference to the nitroso compound. In one or moreembodiments, the molar ratio of the co-functionalizing agent to thenitroso compound may be from about 0.05:1 to about 1:1, in otherembodiments from about 0.1:1 to about 0.8:1, and in other embodimentsfrom about 0.2:1 to about 0.6:1

In one or more embodiments, the nitroso compound (and optionally theco-functionalizing agent) may be introduced to the polymerizationmixture at a location (e.g., within a vessel) where the polymerizationhas been conducted. In other embodiments, the nitroso compound may beintroduced to the polymerization mixture at a location that is distinctfrom where the polymerization has taken place. For example, the nitrosocompound may be introduced to the polymerization mixture in downstreamvessels including downstream reactors or tanks, in-line reactors ormixers, extruders, or devolatilizers.

In one or more embodiments, the nitroso compound (and optionally theco-functionalizing agent) can be reacted with the reactive polymer aftera desired monomer conversion is achieved but before the polymerizationmixture is quenched by a quenching agent. In one or more embodiments,the reaction between the nitroso compound and the reactive polymer maytake place within 30 minutes, in other embodiments within 5 minutes, andin other embodiments within one minute after the peak polymerizationtemperature is reached. In one or more embodiments, the reaction betweenthe nitroso compound and the reactive polymer can occur once the peakpolymerization temperature is reached. In other embodiments, thereaction between the nitroso compound and the reactive polymer can occurafter the reactive polymer has been stored. In one or more embodiments,the storage of the reactive polymer occurs at room temperature or belowunder an inert atmosphere. In one or more embodiments, the reactionbetween the nitroso compound and the reactive polymer may take place ata temperature from about 10° C. to about 150° C., and in otherembodiments from about 20° C. to about 100° C. The time required forcompleting the reaction between the nitroso compound and the reactivepolymer depends on various factors such as the type and amount of thecatalyst used to prepare the reactive polymer, the type and amount ofthe nitroso compound, as well as the temperature at which thefunctionalization reaction is conducted. In one or more embodiments, thereaction between the nitroso compound and the reactive polymer can beconducted for about 10 to 60 minutes.

In one or more embodiments, after the reaction between the reactivepolymer and the nitroso compound (and optionally the co-functionalizingagent) has been accomplished or completed, a quenching agent can beadded to the polymerization mixture in order to protonate the reactionproduct between the reactive polymer and the nitroso compound,inactivate any residual reactive polymer chains, and/or inactivate thecatalyst or catalyst components. The quenching agent may include aprotic compound, which includes, but is not limited to, an alcohol, acarboxylic acid, an inorganic acid, water, or a mixture thereof. Anantioxidant such as 2,6-di-tert-butyl-4-methylphenol may be added alongwith, before, or after the addition of the quenching agent. The amountof the antioxidant employed may be in the range of 0.2% to 1% by weightof the polymer product.

In other embodiments, before the polymerization mixture is quenched witha quenching agent, the reaction product between the reactive polymer andthe nitroso compound is further reacted with an electrophilic reagent.Useful electrophilic reagents include those that can be defined by theformula R—X, where R is a mono-valent organic group, and X is a halogenatom, a sulfonate group, or a thiosulfonate group. Exemplary halogenatoms include fluorine, chlorine, bromine, and iodine atoms. Exemplarysulfonate groups include methanesulfonate, benzenesulfonate,p-toluenesulfonate, and trifluoromethanesulfonate groups. Exemplarythiosulfonate groups include methanethiosulfonate, benzenethiosulfonate,p-toluenethiosulfonate, and trifluoromethanethiosulfonate groups.

Specific examples of useful electrophilic reagents include methylchloride, methyl bromide, methyl iodide, trimethylsilyl chloride,trimethylsilyl bromide, trimethylsilyl iodide, methyl methanesulfonate,methyl benzenesulfonate, methyl p-toluenesulfonate, methyltrifluoromethanesulfonate, methyl methanethiosulfonate, trimethylsilylmethanesulfonate, trimethylsilyl benzenesulfonate, trimethylsilylp-toluenesulfonate, trimethylsilyl trifluoromethanesulfonate, andtrimethylsilyl methanethiosulfonate.

When the reaction involving the electrophilic reagent has beencompleted, a quenching agent and/or an antioxidant may be added to thepolymerization mixture, as described above.

Once the polymerization mixture has been quenched, the variousconstituents of the polymerization mixture may be recovered. In one ormore embodiments, the unreacted monomer can be recovered from thepolymerization mixture. For example, the monomer can be distilled fromthe polymerization mixture by using techniques known in the art. In oneor more embodiments, a devolatilizer may be employed to remove themonomer from the polymerization mixture. Once the monomer has beenremoved from the polymerization mixture, the monomer may be purified,stored, and/or recycled back to the polymerization process.

The polymer product may be recovered from the polymerization mixture byusing techniques known in the art. In one or more embodiments,desolventization and drying techniques may be used. For instance, thepolymer can be recovered by passing the polymerization mixture through aheated screw apparatus, such as a desolventizing extruder, in which thevolatile substances are removed by evaporation at appropriatetemperatures (e.g., about 100° C. to about 170° C.) and underatmospheric or sub-atmospheric pressure. This treatment serves to removeunreacted monomer as well as any low-boiling solvent. Alternatively, thepolymer can also be recovered by subjecting the polymerization mixtureto steam desolventization, followed by drying the resulting polymercrumbs in a hot air tunnel. The polymer can also be recovered bydirectly drying the polymerization mixture on a drum dryer.

While the reactive polymer and the nitroso compound (and optionally theco-functionalizing agent) are believed to react to produce a novelfunctionalized polymer, which can be protonated or further modified, theexact chemical structure of the functionalized polymer produced in everyembodiment is not known with any great degree of certainty, particularlyas the structure relates to the residue imparted to the polymer chainend by the nitroso compound and optionally the co-functionalizing agent.Indeed, it is speculated that the structure of the functionalizedpolymer may depend upon various factors such as the conditions employedto prepare the reactive polymer (e.g., the type and amount of thecatalyst) and the conditions employed to react the nitroso compound (andoptionally the co-functionalizing agent) with the reactive polymer(e.g., the types and amounts of the nitroso compound and theco-functionalizing agent).

In one or more embodiments, one of the products resulting from thereaction between the nitroso compound and the reactive polymer may,after reaction with a quenching agent or an electrophilic reagent,include a functionalized polymer defined by one of the formulae:

where π is a cis-1,4-polydiene chain having a cis-1,4-linkage contentthat is greater than 60%, where β is a mono-valent organic group asdescribed above, and where R′ is a hydrogen atom or a mono-valentorganic group.

In one or more embodiments, the functionalized polymers preparedaccording to this invention may contain unsaturation. In these or otherembodiments, the functionalized polymers are vulcanizable. In one ormore embodiments, the functionalized polymers can have a glasstransition temperature (T_(g)) that is less than 0° C., in otherembodiments less than −20° C., and in other embodiments less than −30°C. In one embodiment, these polymers may exhibit a single glasstransition temperature. In particular embodiments, the polymers may behydrogenated or partially hydrogenated.

In one or more embodiments, the functionalized polymers of thisinvention may be cis-1,4-polydienes having a cis-1,4-linkage contentthat is greater than 60%, in other embodiments greater than about 75%,in other embodiments greater than about 90%, and in other embodimentsgreater than about 95%, where the percentages are based upon the numberof diene mer units adopting the cis-1,4 linkage versus the total numberof diene mer units. Also, these polymers may have a 1,2-linkage contentthat is less than about 7%, in other embodiments less than 5%, in otherembodiments less than 2%, and in other embodiments less than 1%, wherethe percentages are based upon the number of diene mer units adoptingthe 1,2-linkage versus the total number of diene mer units. The balanceof the diene mer units may adopt the trans-1,4-linkage. The cis-1,4-,1,2-, and trans-1,4-linkage contents can be determined by infraredspectroscopy. The number average molecular weight (M_(n)) of thesepolymers may be from about 1,000 to about 1,000,000, in otherembodiments from about 5,000 to about 200,000, in other embodiments fromabout 25,000 to about 150,000, and in other embodiments from about50,000 to about 120,000, as determined by using gel permeationchromatography (GPC) calibrated with polystyrene standards andMark-Houwink constants for the polymer in question. The molecular weightdistribution or polydispersity (M_(w)/M_(n)) of these polymers may befrom about 1.5 to about 5.0, and in other embodiments from about 2.0 toabout 4.0.

Advantageously, the functionalized polymers of this invention exhibitimproved cold-flow resistance and provide rubber compositions thatdemonstrate reduced hysteresis. The functionalized polymers areparticularly useful in preparing rubber compositions that can be used tomanufacture tire components. Rubber compounding techniques and theadditives employed therein are generally disclosed in The Compoundingand Vulcanization of Rubber, in Rubber Technology (2^(nd) Ed. 1973).

The rubber compositions can be prepared by using the functionalizedpolymers alone or together with other elastomers (i.e., polymers thatcan be vulcanized to form compositions possessing rubbery or elastomericproperties). Other elastomers that may be used include natural andsynthetic rubbers. The synthetic rubbers typically derive from thepolymerization of conjugated diene monomers, the copolymerization ofconjugated diene monomers with other monomers such as vinyl-substitutedaromatic monomers, or the copolymerization of ethylene with one or moreα-olefins and optionally one or more diene monomers.

Exemplary elastomers include natural rubber, synthetic polyisoprene,polybutadiene, polyisobutylene-co-isoprene, neoprene,poly(ethylene-co-propylene), poly(styrene-co-butadiene),poly(styrene-co-isoprene), and poly(styrene-co-isoprene-co-butadiene),poly(isoprene-co-butadiene), poly(ethylene-co-propylene-co-diene),polysulfide rubber, acrylic rubber, urethane rubber, silicone rubber,epichlorohydrin rubber, and mixtures thereof. These elastomers can havea myriad of macromolecular structures including linear, branched, andstar-shaped structures.

The rubber compositions may include fillers such as inorganic andorganic fillers. Examples of organic fillers include carbon black andstarch. Examples of inorganic fillers include silica, aluminumhydroxide, magnesium hydroxide, mica, talc (hydrated magnesiumsilicate), and clays (hydrated aluminum silicates). Carbon blacks andsilicas are the most common fillers used in manufacturing tires. Incertain embodiments, a mixture of different fillers may beadvantageously employed.

In one or more embodiments, carbon blacks includes furnace blacks,channel blacks, and lamp blacks. More specific examples of carbon blacksinclude super abrasion furnace blacks, intermediate super abrasionfurnace blacks, high abrasion furnace blacks, fast extrusion furnaceblacks, fine furnace blacks, semi-reinforcing furnace blacks, mediumprocessing channel blacks, hard processing channel blacks, conductingchannel blacks, and acetylene blacks.

In particular embodiments, the carbon blacks may have a surface area(EMSA) of at least 20 m²/g and in other embodiments at least 35 m²/g;surface area values can be determined by ASTM D-1765 using thecetyltrimethylammonium bromide (CTAB) technique. The carbon blacks maybe in a pelletized form or an unpelletized flocculent form. Thepreferred form of carbon black may depend upon the type of mixingequipment used to mix the rubber compound.

The amount of carbon black employed in the rubber compositions can be upto about 50 parts by weight per 100 parts by weight of rubber (phr),with about 5 to about 40 phr being typical.

Some commercially available silicas which may be used include Hi-Sil™215, Hi-Sil™ 233, and Hi-Sil™190 (PPG Industries, Inc.; Pittsburgh,Pa.). Other suppliers of commercially available silica include GraceDavison (Baltimore, Md.), Degussa Corp. (Parsippany, N.J.), RhodiaSilica Systems (Cranbury, N.J.), and J.M. Huber Corp. (Edison, N.J.).

In one or more embodiments, silicas may be characterized by theirsurface areas, which give a measure of their reinforcing character. TheBrunauer, Emmet and Teller (“BET”) method (described in J. Am. Chem.Soc., vol. 60, p. 309 et seq.) is a recognized method for determiningthe surface area. The BET surface area of silica is generally less than450 m²/g. Useful ranges of surface area include from about 32 to about400 m²/g, about 100 to about 250 m²/g, and about 150 to about 220 m²/g.

The pH's of the silicas are generally from about 5 to about 7 orslightly over 7, or in other embodiments from about 5.5 to about 6.8.

In one or more embodiments, where silica is employed as a filler (aloneor in combination with other fillers), a coupling agent and/or ashielding agent may be added to the rubber compositions during mixing inorder to enhance the interaction of silica with the elastomers. Usefulcoupling agents and shielding agents are disclosed in U.S. Pat. Nos.3,842,111, 3,873,489, 3,978,103, 3,997,581, 4,002,594, 5,580,919,5,583,245, 5,663,396, 5,674,932, 5,684,171, 5,684,172 5,696,197,6,608,145, 6,667,362, 6,579,949, 6,590,017, 6,525,118, 6,342,552, and6,683,135, which are incorporated herein by reference.

The amount of silica employed in the rubber compositions can be fromabout 1 to about 100 phr or in other embodiments from about 5 to about80 phr. The useful upper range is limited by the high viscosity impartedby silicas. When silica is used together with carbon black, the amountof silica can be decreased to as low as about 1 phr; as the amount ofsilica is decreased, lesser amounts of coupling agents and shieldingagents can be employed. Generally, the amounts of coupling agents andshielding agents range from about 4% to about 20% based on the weight ofsilica used.

A multitude of rubber curing agents (also called vulcanizing agents) maybe employed, including sulfur or peroxide-based curing systems. Curingagents are described in Kirk-Othmer, ENCYCLOPEDIA OF CHEMICALTECHNOLOGY, Vol. 20, pgs. 365-468, (3^(rd) Ed. 1982), particularlyVulcanization Agents and Auxiliary Materials, pgs. 390-402, and A. Y.Coran, Vulcanization, ENCYCLOPEDIA OF POLYMER SCIENCE AND ENGINEERING,(2^(nd) Ed. 1989), which are incorporated herein by reference.Vulcanizing agents may be used alone or in combination.

Other ingredients that are typically employed in rubber compounding mayalso be added to the rubber compositions. These include accelerators,accelerator activators, oils, plasticizer, waxes, scorch inhibitingagents, processing aids, zinc oxide, tackifying resins, reinforcingresins, fatty acids such as stearic acid, peptizers, and antidegradantssuch as antioxidants and antiozonants.

All ingredients of the rubber compositions can be mixed with standardmixing equipment such as Banbury or Brabender mixers, extruders,kneaders, and two-rolled mills. In one or more embodiments, theingredients are mixed in two or more stages. In the first stage (oftenreferred to as the masterbatch mixing stage), a so-called masterbatch,which typically includes the rubber component and filler, is prepared.To prevent premature vulcanization (also known as scorch), themasterbatch may exclude vulcanizing agents. The masterbatch may be mixedat a starting temperature of from about 25° C. to about 125° C. with adischarge temperature of about 135° C. to about 180° C. Once themasterbatch is prepared, the vulcanizing agents may be introduced andmixed into the masterbatch in a final mixing stage, which is typicallyconducted at relatively low temperatures so as to reduce the chances ofpremature vulcanization. Optionally, additional mixing stages, sometimescalled remills, can be employed between the masterbatch mixing stage andthe final mixing stage. One or more remill stages are often employedwhere the rubber composition includes silica as the filler. Variousingredients including the functionalized polymers of this invention canbe added during these remills.

The mixing procedures and conditions particularly applicable tosilica-filled tire formulations are described in U.S. Pat. Nos.5,227,425, 5,719,207, and 5,717,022, as well as European Patent No.890,606, all of which are incorporated herein by reference. In oneembodiment, the initial masterbatch is prepared by including thefunctionalized polymer of this invention and silica in the substantialabsence of coupling agents and shielding agents.

The rubber compositions prepared from the functionalized polymers ofthis invention are particularly useful for forming tire components suchas treads, subtreads, sidewalls, body ply skims, bead filler, and thelike. Preferably, the functional polymers of this invention are employedin tread and sidewall formulations. In one or more embodiments, thesetread or sidewall formulations may include from about 10% to about 100%by weight, in other embodiments from about 35% to about 90% by weight,and in other embodiments from about 50% to about 80% by weight of thefunctionalized polymer based on the total weight of the rubber withinthe formulation.

Where the rubber compositions are employed in the manufacture of tires,these compositions can be processed into tire components according toordinary tire manufacturing techniques including standard rubbershaping, molding and curing techniques. Typically, vulcanization iseffected by heating the vulcanizable composition in a mold; e.g., it maybe heated to about 140° C. to about 180° C. Cured or crosslinked rubbercompositions may be referred to as vulcanizates, which generally containthree-dimensional polymeric networks that are thermoset. The otheringredients, such as fillers and processing aids, may be evenlydispersed throughout the crosslinked network. Pneumatic tires can bemade as discussed in U.S. Pat. Nos. 5,866,171, 5,876,527, 5,931,211, and5,971,046, which are incorporated herein by reference.

In order to demonstrate the practice of the present invention, thefollowing examples have been prepared and tested. The examples shouldnot, however, be viewed as limiting the scope of the invention. Theclaims will serve to define the invention.

EXAMPLES Example 1 Synthesis of Unmodified cis-1,4-Polybutadiene

To a 2-gallon nitrogen-purged reactor equipped with turbine agitatorblades were added 1383 g of hexane and 3083 g of 20.6 wt % butadiene inhexane. A preformed catalyst was prepared by mixing 8.08 ml of 4.32 Mmethylaluminoxane in toluene, 1.83 g of 20.6 wt % 1,3-butadiene inhexane, 0.65 ml of 0.537 M neodymium versatate in cyclohexane, 7.33 mlof 1.0 M diisobutylaluminum hydride in hexane, and 1.40 ml of 1.0 Mdiethylaluminum chloride in hexane. The catalyst was aged for 15 minutesand charged into the reactor. The reactor jacket temperature was thenset to 65° C. Forty five minutes after addition of the catalyst, thepolymerization mixture was cooled to room temperature. The resultingpolymer cement was coagulated with 12 liters of isopropanol containing 5g of 2,6-di-tert-butyl-4-methylphenol and then drum-dried. The Mooneyviscosity (ML₁₊₄) of the resulting polymer was determined to be 26.5 at100° C. by using a Monsanto Mooney viscometer with a large rotor, aone-minute warm-up time, and a four-minute running time. As determinedby gel permeation chromatography (GPC), the polymer had a number averagemolecular weight (M_(n)) of 111,800, a weight average molecular weight(M_(w)) of 209,500, and a molecular weight distribution (M_(w)/M_(n)) of1.87. The infrared spectroscopic analysis of the polymer indicated acis-1,4-linkage content of 94.4%, a trans-1,4-linkage content of 5.1%,and a 1,2-linkage content of 0.5%.

The cold-flow resistance of the polymer was measured by using a Scottplasticity tester. Approximately 2.6 g of the polymer was molded, at100° C. for 20 minutes, into a cylindrical button with a diameter of 15mm and a height of 12 mm. After cooling down to room temperature, thebutton was removed from the mold and placed in a Scott plasticity testerat room temperature. A 5-kg load was applied to the specimen. After 8minutes, the residual gauge (i.e., sample thickness) was measured andtaken as an indication of the cold-flow resistance of the polymer.Generally, a higher residual gauge value indicates better cold-flowresistance.

The properties of the unmodified cis-1,4-polybutadiene are summarized inTable 1.

TABLE 1 PHYSICAL PROPERTIES OF UNMODIFIED AND MODIFIEDCIS-1,4-POLYBUTADIENE Example No. Example 1 Example 2 Example 3 Example4 Polymer type un- un- NSB- NST- modified modified modified modifiedML₁₊₄ at 26.5 44.2 44.1 37.7 100° C. M_(n) 111,800 130,700 116,200111,000 M_(w) 209,500 260,500 220,500 204,700 M_(w)/M_(n) 1.87 1.99 1.891.84 Cold-flow 1.72 2.28 3.03 2.59 gauge (mm at 8 min.) % cis-1,4 94.495.0 94.3 94.3 % trans-1,4 5.1 4.5 5.2 5.2 % 1,2 0.5 0.5 0.5 0.5

Example 2 Synthesis of Unmodified cis-1,4-Polybutadiene

To a 2-gallon nitrogen-purged reactor equipped with turbine agitatorblades were added 1631 g of hexane and 2835 g of 22.4 wt % butadiene inhexane. A preformed catalyst was prepared by mixing 6.10 ml of 4.32 Mmethylaluminoxane in toluene, 1.27 g of 22.4 wt % 1,3-butadiene inhexane, 0.49 ml of 0.537 M neodymium versatate in cyclohexane, 5.53 mlof 1.0 M diisobutylaluminum hydride in hexane, and 1.05 ml of 1.0 Mdiethylaluminum chloride in hexane. The catalyst was aged for 15 minutesand charged into the reactor. The reactor jacket temperature was thenset to 65° C. Seventy two minutes after addition of the catalyst, thepolymerization mixture was cooled to room temperature. The resultingpolymer cement was coagulated with 12 liters of isopropanol containing 5g of 2,6-di-tert-butyl-4-methylphenol and then drum-dried. Theproperties of the resulting polymer are summarized in Table 1.

Example 3 Synthesis of cis-1,4-Polybutadiene Modified withNitrosobenzene (NSB)

To a 2-gallon nitrogen-purged reactor equipped with turbine agitatorblades were added 1579 g of hexane and 2886 g of 22.0 wt % butadiene inhexane. A preformed catalyst was prepared by mixing 9.55 ml of 4.32 Mmethylaluminoxane in toluene, 2.03 g of 22.0 wt % 1,3-butadiene inhexane, 0.77 ml of 0.537 M neodymium versatate in cyclohexane, 8.67 mlof 1.0 M diisobutylaluminum hydride in hexane, and 1.65 ml of 1.0 Mdiethylaluminum chloride in hexane. The catalyst was aged for 15 minutesand charged into the reactor. The reactor jacket temperature was thenset to 65° C. Fifty minutes after addition of the catalyst, thepolymerization mixture was cooled to room temperature.

About 428 g of the resulting unmodified polymer cement was transferredfrom the reactor to a nitrogen-purged bottle, followed by addition of5.7 ml of 0.41 M nitrosobenzene (NSB) in toluene. The bottle was tumbledfor 30 minutes in a water bath maintained at 65° C. The resultingmixture was coagulated with 3 liters of isopropanol containing 0.5 g of2,6-di-tert-butyl-4-methylphenol and then drum-dried. The properties ofthe resulting NSB-modified polymer are summarized in Table 1.

Example 4 Synthesis of cis-1,4-Polybutadiene Modified with2-Nitrosotoluene (NST)

About 423 g of the pseudo-living polymer cement as synthesized inExample 3 was transferred from the reactor to a nitrogen-purged bottle,followed by addition of 5.4 ml of 0.43 M nitrosotoluene (NST) intoluene. The bottle was tumbled for 30 minutes in a water bathmaintained at 65° C. The resulting mixture was coagulated with 3 litersof isopropanol containing 0.5 g of 2,6-di-tert-butyl-4-methylphenol andthen drum-dried. The properties of the resulting NST-modified polymerare summarized in Table 1.

In FIG. 1, the cold-flow resistance of the unmodified and modifiedcis-1,4-polybutadiene samples synthesized in Examples 1-4 is plottedagainst the polymer Mooney viscosity. The data indicate that, at thesame polymer Mooney viscosity, the NSB- and NST-modifiedcis-1,4-polybutadiene samples show higher residual cold-flow gaugevalues and accordingly better cold-flow resistance than the unmodifiedpolymer.

Examples 5-8 Compounding Evaluation of NSB- and NST-Modifiedcis-1,4-Polybutadiene vs. Unmodified cis-1,4-Polybutadiene

The unmodified and modified cis-1,4-polybutadiene samples produced inExamples 1-4 were evaluated in a carbon black filled rubber compound.The ingredients used to prepare the vulcanizates are presented in Table2, wherein the numbers are expressed as parts by weight per hundredparts by weight of rubber (phr).

TABLE 2 COMPOSITIONS OF RUBBER VULCANIZATES PREPARED FROMCIS-1,4-POLYBUTADIENE Ingredient Amount (phr) Cis-1,4-Polybutadiene 80Polyisoprene 20 Carbon black 50 Oil 10 Wax 2 Antioxidant 1 Zinc oxide2.5 Stearic acid 2 Accelerators 1.3 Sulfur 1.5 Total 170.3

The Mooney viscosity (ML₁₊₄) of the uncured compound was determined at130° C. by using a Alpha Technologies Mooney viscometer with a largerotor, a one-minute warm-up time, and a four-minute running time. Thetensile strength at break (T_(b)) and the elongation at break (E_(b))were determined according to ASTM D412. The Payne effect data (ΔG′) andhysteresis data (tan δ) of the vulcanizates were obtained from a dynamicstrain sweep experiment, which was conducted at 50° C. and 15 Hz withstrain sweeping from 0.1% to 20%. ΔG′ is the difference between G′ at0.1% strain and G′ at 20% strain. The physical properties of thevulcanizates are summarized in Table 3 and FIG. 2.

TABLE 3 PHYSICAL PROPERTIES OF RUBBER VULCANIZATES PREPARED FROMCIS-1,4-POLYBUTADIENE Example No. Example 5 Example 6 Example 7 Example8 Polymer used Example 1 Example 2 Example 3 Example 4 Polymer type Un-un- NSB- NST- modified modified modified modified Compound 51.8 69.357.1 57.2 ML₁₊₄ at 130° C. T_(b) at 23° C. 14.9 15.4 17.2 17.6 (MPa)E_(b) at 23° C. (%) 389 391 397 432 ΔG′ (MPa) 3.78 3.63 2.45 2.35 tanδat 50° C., 0.135 0.128 0.116 0.119 3% strain

As can be seen in Table 3 and FIG. 2, the NSB- and NST-modifiedcis-1,4-polybutadiene samples give lower tan δ at 50° C. than theunmodified polymer, indicating that the modification ofcis-1,4-polybutadiene with NSB and NST reduces hysteresis. The NSB- andNST-modified cis-1,4-polybutadiene samples also give lower ΔG′ than theunmodified polymer, indicating that the Payne Effect has been reduceddue to the stronger interaction between the modified polymer and carbonblack.

Various modifications and alterations that do not depart from the scopeand spirit of this invention will become apparent to those skilled inthe art. This invention is not to be duly limited to the illustrativeembodiments set forth herein.

What is claimed is:
 1. A method for preparing a functionalized polymer,the method comprising the steps of: (i) polymerizing monomer with acoordination catalyst to form a reactive polymer; and (ii) reacting thereactive polymer with a nitroso compound.
 2. The method of claim 1,where the nitroso compound is defined by the formula β—N═O, where β is amono-valent organic group and —N═O is a nitroso group.
 3. The method ofclaim 2, where the mono-valent organic group β is bonded to the nitrosogroup through a carbon atom, a nitrogen atom, an oxygen atom, or asulfur atom that resides within the β group.
 4. The method of claim 2,where the mono-valent organic group β is selected from the groupsconsisting of hydrocarbyl groups, substituted hydrocarbyl groups,protected amino groups, hydrocarbyloxy groups, substitutedhydrocarbyloxy groups, hydrocarbylthio groups, and substitutedhydrocarbylthio groups.
 5. The method of claim 2, where the nitrosocompound is selected from the group consisting of C-nitroso compounds,N-nitroso compounds, O-nitroso compounds, and S-nitroso compounds. 6.The method of claim 5, where the nitroso compound is a C-nitrosocompound.
 7. The method of claim 5, where the nitroso compound is anN-nitroso compound.
 8. The method of claim 5, where the nitroso compoundis an O-nitroso compound.
 9. The method of claim 5, where the nitrosocompound is an S-nitroso compound.
 10. The method of claim 6, where thenitroso compound is a C-nitroso compound selected from the groupconsisting of nitrosomethane, nitrosoethane, 1-nitroso-n-propane,2-nitroso-n-propane, 1-nitroso-n-butane, 2-methyl-2-nitrosopropane,1-nitroso-n-pentane, 1-nitroso-n-hexane, 1-nitroso-n-heptane,1-nitroso-n-octane, 1-nitroso-n-nonane, 1-nitroso-n-decane,1-nitroso-n-dodecane, nitrosocyclopentane, nitrosocyclohexane,nitrosocyclooctane, nitrosobenzene, 2-nitrosotoluene, 3-nitrosotoluene,4-nitrosotoluene, N,N-dimethyl-4-nitrosoaniline,N,N-diethyl-4-nitrosoaniline, 2-nitrosopyridine, 3-nitrosopyridine,4-nitrosopyridine, nitrosopyrazine, 2-nitrosopyrimidine,4-nitrosopyrimidine, 5-nitrosopyrimidine, 3-nitrosopyridazine,4-nitrosopyridazine, 2-nitrosoquinoline, 3-nitrosoquinoline,4-nitrosoquinoline, 1-nitrosophthalazine, 2-nitrosoquinazoline,4-nitrosoquinazoline, 2-nitrosoquinoxaline,2-nitroso-1,10-phenanthroline, 3-nitroso-1,10-phenanthroline,4-nitroso-1,10-phenanthroline, 5-nitroso-1,10-phenanthroline,1-nitrosophenazine, 2-nitrosophenazine, N-methyl-2-nitrosopyrrolidine,N-methyl-2-nitrosopyrrole, N4-methyl-3-nitrosopyrrole,N-meth-2-nitrosoimidazole, N-methyl-4 nitrosoimidazole,N-methyl-5-nitrosoimidazole, N-methyl-3-nitrosopyrazole,N-methyl-4-nitrosopyrazole, N-methyl-5-nitrosopyrazole,N-methyl-2-nitrosopiperidine, N-methyl-2-nitrosohomopiperidine,N-methyl-2-nitrosomorpholine, N-(trimethylsilyl)-2-nitrosopyrrolidine,N-(trimethylsilyl)-2-nitrosopyrrole,N-(trimethylsilyl)-3-nitrosopyrrole,N-(trimethylsilyl)-2-nitrosoimidazole,N-(trimethylsilyl)-4-nitrosoimidazole,N-(trimethylsilyl)-5-nitrosoimidazole,N-(trimethylsilyl)-3-nitrosopyrazole,N-(trimethylsilyl)-4-nitrosopyrazole,N-(trimethylsilyl)-5-nitrosopyrazole,N-(trimethylsilyl)-2-nitrosopiperidine,N-(trimethylsilyl)-2-nitrosohomopiperidine, andN-(trimethylsilyl)-2-nitrosomorpholine.
 11. The method of claim 7, wherethe nitroso compound is an N-nitroso compound selected from the groupconsisting of N-nitrosopyrrolidine, N-nitrosopyrrole,N-nitrosoimidazole, N-nitrosopyrazole, N-nitrosopiperidine,N-nitrosohomopiperidine, N-nitrosomorpholine, N-nitrosonornicotine,N-nitrosodimethylamine, N-nitrosodiethylamine,N-nitrosodi-n-propylamine, N-nitrosodiisopropylamineN-nitrosodi-n-butylamine, N-nitrosodiisobutylamine,N-nitrosodi-t-butylamine, N-nitrosodineopentylamine,N-nitrosodiphenylamine, N-nitrosodibenzylamine,N-nitrosodi-2-tolylamine, N-nitrosodi-3-tolylamine,N-nitrosodi-4-tolylamine, N-nitrosodi-2-pyridylamine,N-benzyl-N-nitroso-p-toluenesulfonamide,N-nitrosobis(trimethylsilyl)amine, N-nitrosobis(triethylsilyl)amine,N-nitrosobis(triisopropylsilyl)amine, N-nitrosobis(triphenylsilyl)amine,and N-nitroso (trimethylsilyl)(methyl)amine.
 12. The method of claim 8,where the nitroso compound is an O-nitroso compound selected from thegroup consisting of methyl nitrite, ethyl nitrite, n-propyl nitrite,isopropyl nitrite, n-butyl nitrite, isobutyl nitrite, t-butyl nitrite,neopentyl nitrite, benzyl nitrite, phenyl nitrite, trimethylsilylnitrite, triethylsilyl nitrite, triisopropylsilyl nitrite, andtriphenylsilyl nitrite.
 13. The method of claim 9, where the nitrosocompound is an S-nitroso compound selected from the group consisting ofmethyl thionitrite, ethyl thionitrite, n-propyl thionitrite, isopropylthionitrite, n-butyl thionitrite, isobutyl thionitrite, t-butylthionitrite, neopentyl thionitrite, benzyl thionitrite, phenylthionitrite trimethylsilyl thionitrite, triethylsilyl thionitrite,triisopropylsilyl thionitrite, and triphenylsilyl thionitrite.
 14. Themethod of claim 1, where the reaction product from said step of reactingis subsequently protonated.
 15. The method of claim 1, where thereaction product from said step of reacting is subsequently reacted witha compound defined by the formula R—X, where R is a mono-valent organicgroup, and X is a halogen atom, a sulfonate group, or a thiosulfonategroup.
 16. The method of claim 1, where the coordination catalyst is alanthanide-based catalyst.
 17. The method of claim 16, where thelanthanide-based catalyst includes (a) a lanthanide compound, (b) analkylating agent, and (c) a halogen-containing compound.
 18. The methodof claim 17, where the alkylating agent includes an aluminoxane and anorganoaluminum compound represented by the formula AlR_(n)X_(3-n), whereeach R, which may be the same or different, is a mono-valent organicgroup that is attached to the aluminum atom via a carbon atom, whereeach X, which may be the same or different, is a hydrogen atom, ahalogen atom, a carboxylate group, an alkoxide group, or an aryloxidegroup, and where n is an integer of 1 to
 3. 19. The method of claim 1,where said step of polymerizing monomer takes place within apolymerization mixture including less than 20% by weight of organicsolvent.
 20. A functionalized cis-1,4-polydiene defined by the formula:

where π is a cis-1,4-polydiene chain having a cis-1,4-linkage contentthat is greater than 60%, where β is a mono-valent organic group, andwhere R′ is a hydrogen atom or a mono-valent organic group.
 21. Thefunctionalized cis-1,4-polydiene of claim 20, where thecis-1,4-polydiene chain has a cis-1,4-linkage content that is greaterthan 75%.
 22. The functionalized cis-1,4-polydiene of claim 20, wherethe cis-1,4-polydiene chain has a cis-1,4-linkage content that isgreater than 90%.
 23. A functionalized cis-1,4-polydiene prepared by thesteps of: (i) polymerizing conjugated diene monomer with a coordinationcatalyst to form a reactive cis-1,4-polydiene having a cis-1,4-linkagecontent that is greater than 60%; and (ii) reacting the reactivecis-1,4-polydiene with a nitroso compound.